P
R
O
O
F
O
N
L
Y
12
Pilot-Scale Decontamination of Soil Polluted with As, Cr,
31
Cu, PCP, and PCDDF by Attrition and Alkaline Leaching
4
Sabrine Metahni
1; Lucie Coudert
2; Myriam Chartier
3; Jean-Francois Blais
4;
5
Guy Mercier
5; and Simon Besner
66 Abstract: Recently, an efficient and promising process was developed to allow the removal of As, Cr, Cu, pentachlorophenol (PCP), and
7 polychlorodibenzo-dioxins and furans (PCDDF) from soil using alkaline leaching. The present study evaluates the performance and the
8 robustness of this decontamination process for the treatment of four different polluted soils by attrition and alkaline leaching at a pilot scale.
9 The attrition process carried out on the coarse fraction (>0.125 mm) allowed the removal of 24–42% of As, 0–13% of Cr, 23–46% of Cu, 0–
10 85% of PCP, and 17–64% of PCDDF from the different contaminated soils. Removal yields of 87–95% of As, 50–72% of Cr, 73–84% of Cu,
11 52–100% of PCP, and 27–73% of PCDDF were obtained after three leaching steps (½NaOH ¼ 1 M; ½Cocamydopropylbetaine—BW ¼ 3%
12 (w/w); t ¼ 2 h; pulp density ½PD ¼ 10% [w/v]) conducted on the fine fraction (<0.125 mm). The performance of both attrition and alkaline 13 leaching processes seemed to be influenced by the nature of the soil and the type and initial level of contaminants present in the soils.
14 However, the entire leaching process seemed to be highly efficient, allowing the simultaneous reduction of concentrations of inorganic
15 and organic contaminants. The cost, including direct and indirect costs, were estimated between US$214 and 454 per ton of treated soil,
16 depending on the nature of the soil and the initial level of contamination. DOI:10.1061/(ASCE)EE.1943-7870.0001255. © 2017 American
17 Society of Civil Engineers.
18 Author keywords: Contaminated soils; Polychlorodibenzo-dioxins and furans (PCDDF); Pentachlorophenol (PCP); Metal; Attrition;
19 Alkaline leaching; Pilot scale.
20 Introduction
212 Overthe last
3 few decades, soil contaminated by organic and/or
in-22 organic compounds have become a major concern, affecting human
23 health and causing a serious threat to the environment (Napola et al.
24 2006;Mouton et al. 2009). The primary reasons for soil
contami-25 nation are improper industrial discharge, inappropriate disposal
26 of wastes, mine tailings, the use of pesticides, combustion and the
27 industry of wood preservation, and certain natural resources
28 (Kulkarni et al. 2008;Mao et al. 2015). In North America,
numer-29 ous sites contaminated by both organic and inorganic compounds
30
requiring remediation have been listed, including wood
preserva-31
tion industry sites. Since the 1970s, preservative agents have been
32
applied to wood structures to protect them from insects and fungal
33
attacks and enhance their service lifetime by 20–50 years (Janin
34
2009). Over the last few decades, the most commonly used wood
35
preservative agents are chromated copper arsenate (CCA) and
36
pentachlorophenol (PCP). The leaching of these preservative
37
agents [As, Cr, Cu, PCP, and polychlorodibenzo-dioxins and furans
38
(PCDDF)] from treated wood structures led to the contamination
39
of soil by both organic and inorganic compounds. Indeed, some
40
researchers highlighted that the inappropriate management and/
41
or storage of treated wood during the last few decades is
respon-42
sible for the contamination of several sites across the world (Cooper
43
and Ung 1997;Stefanovic and Cooper 2005;Hasan et al. 2010).
44
Usually, these soils are contaminated by metals (As, Cr, Cu) and
45
organic compounds, such as PCP and PCDDF (Reynier 2012).
46
Currently, the only available options for the remediation of soils
47
contaminated by both organic and inorganic compounds are limited
48
to excavation, followed by thermal desorption to destroy organic
49
contaminants, followed by the immobilization of inorganic
contam-50
inants or excavation, followed by disposal at off-site secured waste
51
landfill sites (Dermont et al. 2008). However, these management
52
options are becoming nonpreferable owing to the regulations
53
regarding incineration and landfill leachate controls, which are
be-54
coming increasingly stringent (Reynier et al. 2013). In the last
55
few years, various processes including thermal, biological, and
56
physicochemical technologies have been the subject of several
57
studies to allow the rehabilitation of soils contaminated by As,
58
Cr, Cu, PCP, and PCDDF (Mouton et al. 2009). The thermal
meth-59
ods showed good results for PCP and PCDDF removal, but these
60
technologies are inefficient for the removal of metals from
conta-61
minated soils (Lecomte 1998; Reynier 2012; Dufresne 2013).
62
Kasai et al. (2004) showed that a thermal desorption method that
1Ph.D. Student, Institut National de la Recherche Scientifique (Centre
Eau, Terre et Environnement), Univ. du Québec, 490 Rue de la Couronne, QC, Canada G1K 9A9. E-mail: [email protected]
2Research Associate, Institut National de la Recherche Scientifique
(Centre Eau, Terre et Environnement), Univ. du Québec, 490 Rue de la Couronne, QC, Canada G1K 9A9. E-mail: [email protected]
3Research Assistant, Institut National de la Recherche Scientifique
(Centre Eau, Terre et Environnement), Univ. du Québec, 490 Rue de la Couronne, QC, Canada G1K 9A9. E-mail: [email protected]
4Professor, Institut National de la Recherche Scientifique (Centre Eau,
Terre et Environnement), Univ. du Québec, 490 Rue de la Couronne, QC, Canada G1K 9A9 (corresponding author). E-mail: jean-francois.blais@ete. inrs.ca
5Professor, Institut National de la Recherche Scientifique (Centre Eau,
Terre et Environnement), Univ. du Québec, 490 Rue de la Couronne, QC, Canada G1K 9A9. E-mail: [email protected]
6Project Manager, Institut de Recherche d’Hydro–Québec, 1800, Boul,
Lionel–Boulet, Varennes, QC, Canada J3X 1S1. E-mail: besner. [email protected]
Note. This manuscript was submitted on April 12, 2016; approved on March 1, 2017No Epub Date. Discussion period open until 0, 0; separate discussions must be submitted for individual papers. This paper is part of the Journal of Environmental Engineering, © ASCE, ISSN 0733-9372.
P
R
O
O
F
O
N
L
Y
63 allows more than 98.9% removal of PCDDF in a laboratory-scale64 experiment could be efficiently used for the remediation of
conta-65 minated soil. Bioremediation methods usually referred to the use
66 of microorganisms such as fungi and bacteria to break down
com-67 plex organic contaminants into simpler compounds such as CO2,
68 H2O, CH4, and chlorine (Doyle 2008). However, these methods
69 required long periods to remove or degrade organic contaminants,
70 ranging from a few weeks to a few months, and their applicability
71 to soils contaminated by metals and PCDDF is restricted (Lecomte
72 1998). Soil washing is another method of treatment that can be used
73 to remediate both organic and inorganic contaminants using
74 physicochemical treatment methods. Chemical extraction can
75 be achieved using different reagents including inorganic (sulfuric,
76 nitric, phosphoric acids) or organic acids (acetic, citric acid)
77 (Subramanian et al. 2010; Lafond et al. 2012), chelating agents
78 [ethylenediaminetetraacetic acid (EDTA), ethylenediamine
disuc-794 cinic acid (EDSS)] (Rivero-Huguet and Marshall 2011;
805 Pociecha and Lestan 2012;Voglar and Lestan 2013
6 ), or surfactants
81 [Tween 80 (TW), cocamidopropylhydroxysultaine (CAS),
cocami-82 dopropylbetaine (BW), Brij 35, and Brij 98] (Mouton et al. 2009;
83 Rivero-Huguet and Marshall 2011; Reynier 2012; Torres et al.
84 2012). Physical separation may be performed alone or in
combi-85 nation with chemical treatments to enhance the performance of
86 contaminant removal from coarse soil fraction while reducing the
87 operational costs. Physical separation methods such as mechanical
88 screening, froth flotation, magnetic separation, attrition scrubbing
89 and hydrodynamic classification can be efficiently used to remove
90 metals from soil and concentrate these contaminants into small
91 quantities of soil, especially for the rehabilitation of sites with large
92 amounts of contaminated soil owing to the low operational costs of
93 these technologies (Dermont et al. 2008). The most common
physi-94 cal separation method used for the decontamination of coarse
95 particles of soil contaminated by both organic and inorganic
com-96 pounds is attrition (Taillard 2010;Bisone 2012). Indeed,
mechani-97 cal rotation used during the attrition processes caused collision
98 between large particles that released the contaminants and
concen-99 trated them into the fine fraction (Bergeron et al. 1999). An efficient
100 leaching process using flotation in acidic media (sulfuric acid) in
101 the presence of an amphoteric surfactant (BW) was identified to
102 remove organic compounds and metals from soil contaminated
1037 by As, Cr, Cu, PCP, and PCDDF. According to the authors, the
104 results showed that removal yields of 82–93% of As, 30–80%
105 of Cr, 79–90% of Cu, and 36–78% of PCP were obtained
106 from soil initially containing ½Asi¼ 50–250 mg=kg, ½Cri¼
107 35–220 mg=kg, ½Cui¼ 80–350 mg=kg, and ½PCPi¼
108 2.5–30 mg=kg (Reynier et al. 2013). Reynier (2012) also
high-109 lighted that more than 60% of As, 32% of Cr, 77% of Cu, and
110 87% of PCP can be removed from contaminated soil after three
111 leaching steps, 2 h each, carried out at 80°C with pulp density
112 (PD) fixed at 10% (w/w) in the presence of sodium hydroxide
113 (0.5 M) and a surfactant½ðBWÞ ¼ 2%ðw=wÞ. However, the
efflu-114 ents produced during this leaching process contained high
concen-115 trations of contaminants and required a treatment to allow their
116 recycling into the leaching process or their discharge in municipal
117 sewers. Over the last few decades, precipitation and coagulation of
118 metals have been the primary methods used for the removal of
119 inorganic and organic contaminants from acidic or basic industrial
120 effluents. Typically, metals can be precipitated as hydroxides,
sul-121 fides, or carbonates from the effluents. Previous studies showed the
122 efficiency of ferric salts for the removal of As, Cr, and Cu from
123 effluents (Blais et al. 2008;Coudert et al. 2014).
124 The objective of this study was to evaluate the performance and
125 the robustness of an alkaline leaching process to remove As, Cr,
126 Cu, PCP, and PCDDF from the fine soil fraction (<0.125 mm)
127
combined with an attrition process for the removal of contaminants
128
from coarse particles (>0.125 mm) at a pilot plant scale to reduce
129
the costs of decontamination.
130 Material and Methods
131
Soil Sampling and Characterization
132
Four soil samples (D1, G2, S1, and S3) contaminated by As, Cr,
133
Cu, PCP, and PCDDF were collected from different industrial
134
areas. For each site, excavation of contaminated soils was
per-135
formed using an excavator at a depth of 0–30 cm. More than
136
25 kg of soils were collected and stored in high-density
polyethyl-137
ene (HDPE) containers. Soils were then wet-sieved for 20 min
138
through four different sieves (12, 4, 1, and 0.125 mm) using a
139
mechanical Sweco to determine the particle-size distribution of 8
140
each soil and collect the different fractions used in this study
141
(>12, 4–12, 1–4, 0.125–4, and <0.125 mm). For the determination
142
of inorganic (As, Cr, Cu) and organic (PCP and PCDDF)
contam-143
inant contents in the different soil fractions, soil samples were
144
crushed using a Fristh ball mill (Pulverissette model 6) to obtain
145
homogenous samples.
146
Attrition Experiments
147
Fig.1 shows a diagram of the entire process used for the
decon-148
tamination of the four soils contaminated by As, Cr, Cu, PCP, and
149
PCDDF. Attrition experiments were applied to the coarse fractions
150
(4–12, 1–4, and 0.125–1 mm) of four different soil samples, which
151
represented between 87 and 95% (w/w) of the total soil. Soil
par-152
ticles larger than 12 mm were not treated by attrition because of the
153
low levels of inorganic (As, Cr, Cu) and organic (PCP, PCDDF)
154
contaminations. The attrition process consisted of three 20-min
at-155
trition steps performed in a 10-L capacity stainless steel reactor
156
equipped with three deflectors and a mechanical stirrer (Light
157
EV1 P25 AXFLOW, New York). The mixing speed was fixed
158
at 1,700 rpm. Attrition experiments were carried out onto 2 kg
159
of soil sample mixed with tap water (pH around 7) to obtain a
160
40% PD (w/w). After each 20-min attrition step, treated soils were
161
separated from the water using 2, 0.5, and 0.125 mm sieves for the
162
4–12, 1–4, and 0.125–1 mm soil fractions, respectively. The treated
163
soil was then washed with 4 L of tap water before being
reintro-164
duced to the attrition process to undergo the next attrition step.
165
After the third attrition step, the soil samples were transferred in
166
a 20-L plastic reactor and were then rinsed with 4 L of tap water
167
using a Karcher electric sprayer (140 kg=cm2, Québec, QC,
Can-168
ada) before being sieved. Approximately 2 L of tap water was
169
sprayed on the different sieves (less than 0.125 mm for the
170
0.125–1 mm fraction, less than 0.5 mm for the 1–2 mm fraction,
171
and less than 1 mm for the 2–4 mm fraction) to rinse each treated
172
soil fraction. After the attrition process, each fraction of the
differ-173
ent soils studied were dried at 60°C in a vacuum oven and analyzed
174
to determine the residual concentrations of inorganic and organic
175
contaminants.
176
Leaching Experiments
177
Leaching experiments were performed on the fine fraction
178
(<0.125 mm) of the four different soils studied. The alkaline
con-179
ditions of leaching (temperature, pH, PD, number of steps) were
180
optimized in a previous study (Reynier 2012). The leaching process
181
consisted of three leaching steps, 2 h each, followed by one rinsing
182
step of 15 min. For all leaching assays, the PD was fixed at 10%
183
P
R
O
O
F
O
N
L
Y
184 Leaching experiments were performed in a 25-L capacity stainless
185 steel reactor by mixing 2 kg of soil with 18 L of alkaline solution
186 (1 M NaOH, Laboratories MAT, Quebec, Canada). The initial pH
187 value of the pulp was around 13–13.5 all along the experiments
188 (without any addition of acid or basis). To enhance the removal
189 of organic contaminants, an amphoteric surfactant (BW) was added
190 before each washing step, and its concentration was fixed at 3%
191 (w/v). The leaching steps were conducted at80 7°C using a
hot-192 plate (Thermo Scientific Remote-Control Hotplates, Montreal, QC,
193 Canada), whereas the rinsing steps were carried out at room
tem-194 perature. During the leaching and rinsing steps, the mixing speed
195 was fixed at 1,700 rpm using a mechanical stirrer (Light EV1 P25
196 AXFLOW, New York, NY). After each leaching and rinsing step,
197 solid-to-liquid separation was carried out by removing most of the
198 liquid using a lamella settler with a capacity of 20 L, a settling area
199 of0.44 m2, a length of 21 cm, and a height of 32 cm (Fiberglass, 14
200 lamella, Plastiver, Québec, QC, Canada). After the leaching and the
201 rinsing steps, soil samples were collected and then dried at 60°C
202 before being analyzed to determine the residual concentrations
203 of PCP, PCDDF, and metals.
204 Alkaline Leachates Treatment by Precipitation
205 Leachate treatment was performed by precipitation–coagulation
206 using 1 L of the effluent emerging from the first leaching step
207 to concentrate the contaminants present in small amounts of sludge.
208 The precipitation–coagulation experiments were performed in
2099 Imhoffcones. A solution of sulfuric acid (93% H2SO4) was used
210 to reduce the pH of the leaching solution from 13.0–13.5 to
211
7.5–8.0. Between 2.95 and 4.30 g=L of a solution of ferric sulfate
212
[9.65% of iron (w/w), Chemco, Saint-Augustin-de-Desmaures,
213
QC, Canada] was added to the solution under agitation to improve
214
the removal of As. Indeed, some research showed that the addition
215
of ferric ions during the precipitation allowed the formation of a
216
precipitate of iron arsenate (FeAsO4·2H2O) and the adsorption
217
of As ions onto ferric hydroxide molecules, thus improving the
re-218
moval of As from effluents (Coudert et al. 2014). The addition of
219
ferric sulfate led to an acidification of the solution that depended on
220
the amount added. To avoid any resolubilization of As, Cr, Cu, and
221
PCP resulting from the acidification observed, a solution of sodium
222
hydroxide [ðNaOHÞ ¼ 0.5 M] was then added to adjust the final
223
pH of the solution between 7.0 and 7.3. The solution was then left
224
to settle overnight, and the sludge produced was then collected and
225
dried at 60°C. The concentrations of inorganic and organic
contam-226
inants were determined in the different sludge samples collected.
227
Analytical Methods
228
Metal Analysis
229
Metal contents in the soil before and after treatment were
deter-230
mined in the laboratories at the National Institute of Scientific
Re-231
search (INRS) by inductively plasma coupled to atomic emission
232
spectroscopy (ICP-AES) (Vista Ax CCO simultaneous ICP-AES,
233
Varian, Mississauga, ON, Canada) after digestion of 0.5 g of dry
234
soil samples in the presence of nitric and hydrochloric acids (HNO3
235
and HCl) according to Method 3030I (APHA 1999). Each soil
sam-236
ple was digested and analyzed in triplicate. During each series of
P
R
O
O
F
O
N
L
Y
237 analysis, digestion blanks, reference certified soil samples [CNS238 392-050, PQ-1, lot No. 7110C513, CANMET, Canadian Certified
239 Reference Materials Project (CCRMP)], and certified standard
so-240 lutions (Multi-elements standard, Catalog No. C00-061-403, SCP
241 Science, Lasalle, QC, Canada) were analyzed to ensure the quality
242 of the analysis.
243 Organic Contaminant Analysis
244 PCP contents in the soil before and after treatment were determined in
24510 the laboratoriesaccording to the Centre d’expertise en analyse
envi-246 ronnementale du Québec (CEAEQ) method (CEAEQ 2013) after the
247 solubilization of PCP from 20 g of soil by Soxhlet extraction in the
248 presence of methylene chloride (300 mL). PCP was then transferred
249 to an aqueous phase (solution of sodium hydroxide at20 g=L) by
250 liquid/liquid extraction to perform a derivatization step in the presence
251 of anhydrous acetate and a solution of potassium carbonate (75%, v/
252 v). After 12 h, a liquid/liquid extraction step was carried out using
253 methylene chloride. A solution of phenanthren-d10(internal standard) 254 was added, and then PCP analysis was performed by gas
chromatog-255 raphy with mass spectroscopy (GC-MS) (Perkin Elmer, model
256 Clarus 500, column type Rxi-17,30 m × 0.25 mm × 0.25 μm).
257 The analysis of the 17 toxic congeners of PCDDF was
per-258 formed according to the CEAEQ method MA. 400-D.F. 1.1
259 (CEAEQ 2011) by an external laboratory (Wellington Laboratories,
260 Guelph, ON, Canada).
261 pH Measurements
26211 The pH was determined using a pH-meter (Accumet Model915)
263 equipped with a double junction Cole-Parmer electrode with an Ag/
264 AgCl reference cell. Before each series of measurements, certified
265 buffer solutions (pH¼ 2, 4, 7, and 10) were used to calibrate the
266 pH-meter. The total solid contents were measured according to the
267 APHA method 2540D (APHA 1999).
268 Economic Analysis
269 The direct and indirect costs related to the treatment of the four
270 different soils contaminated by As, Cr, Cu, PCP, and PCDDF
271
by attrition (>0.125 mm soil fraction) and alkaline leaching
272
(<0.125 mm) were estimated for a decontamination plant able to
273
treat 15,000 t of soil per year (operating period:350 d=year;
treat-274
ment capacity: 48 t=d; operating efficiency factor: 90%). The
275
decontamination process plant was designed in countercurrent
276
mode, which means that the effluents produced were recycled into
277
the decontamination process to reduce the consumption of
chem-278
icals and water. In the economic analysis, the operating cost
in-279
cluded the costs related to the use of chemical products such as
280
H2SO4 [US$80=t for a solution at 93% (w/w)], BW (US$1=kg),
281
Fe2ðSO4Þ3(US$200=t), and NaOH (US$500=t); the consumption
282
of electricity (US$0.07=kWh), water (US$0.50=m3), and fuel
283
(US$3.50=t); and the labor (US$25=h). The costs related to the
284
transport and disposal of contaminated soils (US$120=t), highly
285
contaminated soils (US$500=t for the transport, thermal
destruc-286
tion, and landfilling), and inorganic and organic hazardous wastes
287
including sludge coming from the precipitation–coagulation
288
(US$500=t) were also included in the estimation of the direct costs.
289
The indirect costs included the administrative staff, insurance and
290
taxes, research and development, and capital costs. The capital
291
costs were evaluated using a 10-year reimbursement period for
292
all equipment required for the treatment of soils by attrition and
293
leaching and for the treatment of leachates by precipitation with
294
a 5% annual interest rate.
295 Results and Discussion
296
Soil Characteristics
297
Table1presents the concentration of As, Cr, Cu, PCP measured in
298
each soil fraction (>12, 4–12, 1–4, 0.125–1, and <0.125 mm) of
299
the four different soils studied and the soil fraction proportion.
Ac-300
cording to the particle-size distribution of the different soils, the
301
coarse particles (>0.125 mm) represented the majority of the soils
302
with proportions ranging from 80.8 to 96.3%, whereas fine
par-303
ticles (<0.125 mm) represented only between 3.7 and 19.2% of
Table 1. Concentrations of Contaminants Measured in the Different Soil Fractions from Four Different Soils Studied
T1:1 Soil Fraction Soil proportion (w/w) (%) As (mg=kg) Cr (mg=kg) Cu (mg=kg) PCP (mg=kg)
T1:2 D1 >12 mm 22.8 38.4 26.0 50.0 0.36 T1:3 4–12 mm 23.8 37.2 134 61.0 0.04 T1:4 1–4 mm 22.5 19.6 1.6 183 4 88.0 3.4 0.04 T1:5 0.125–1 mm 19.2 45.3 4.8 143 9 136 6 0.23 T1:6 <0.125 mm 11.7 286 22 374 44 559 73 4.43 T1:7 Entire soil 100 64.2 150 137 0.66 T1:8 G2 4–25 mm 42.1 52.2 24.0 98.0 0.15 T1:9 1–4 mm 19.4 70.5 3.5 75.0 2.8 134 8 0.95 T1:10 0.125–1 mm 19.2 83.8 5.3 153 8 168 8 0.13 T1:11 <0.125 mm 19.2 776 6 575 8 956 7 5.95 T1:12 Entire soil 100 201 164 283 1.41 T1:13 S1 >12 mm 22.7 41.8 17.0 60.0 5.03 T1:14 4–12 mm 21.0 37.0 16.0 53.0 1.89 T1:15 1–4 mm 39.2 34.1 0.9 258 2 67.0 1.4 6.17 T1:16 0.125–1 mm 13.4 52.2 1.7 247 8 89.0 0.1 8.56 T1:17 <0.125 mm 3.70 544 80 401 59 681 111 54.7 T1:18 Entire soil 100 57.7 156 88.1 7.12 T1:19 S3 >12 mm 15.6 7.33 7.00 27.0 2.10 T1:20 4–12 mm 23.4 7.05 7.00 25.0 8.40 T1:21 1–4 mm 27.9 7.19 0.40 7.19 0.20 7.05 0.30 18.4 T1:22 0.125–1 mm 24.3 75.0 4.3 66.0 3.6 135 8 21.3 T1:23 <0.125 mm 8.74 664 8 509 29 830 11 191 T1:24 Entire soil 100 81.1 65.2 117 29.3
P
R
O
O
F
O
N
L
Y
304 all soils. For soil samples G2, S1, and S3, the texture class of the305 entire soil is silty sand, whereas the texture class of D1 is sand.
306 The concentrations of As, Cr, Cu, and PCP measured in all soil
307 samples were very different among the four soils studied, ranging
308 from 57.7 to 201 mg As=kg, from 65.2 to 164 mg Cr=kg, from
309 88.1 to283 mg Cu=kg, and from 0.66 to 29.3 mg PCP=kg. The
dis-310 tribution of the contaminants in the four different soils studied
311 showed that the finer fraction (<0.125 mm) was most contaminated
312 than the coarser fraction (>0.125 mm). According to Anderson
313 et al. (1999), the increase of surface area, cationic exchange
poten-314 tial in the fine fraction, and the innate shape of silts and clays
315 are important parameters favoring the attraction of contaminants
316 to the fine fractions of soils. Dermont et al. (2008) also reported
317 that the contaminants are generally associated with fine particles
318 (clay and silt), which are more potentially reactive as they have
319 a higher surface area than coarser particles.
32012 Table 2 presents the toxicity factors and the associated toxic
321 equivalent quantity (TEQ) values for each dioxin and furan
conge-322 ner present in the coarse fraction (>0.125 mm) and the fine fraction
323 (<0.125 mm) of the four different soils. These results showed that
324 the 17 congeners known to be toxic were present in the coarse and
325 fine fractions of all soils. According to these results, the fixation of
326 PCDDF seemed to more important and favorable on the finer
frac-327 tion for the different soils; the concentrations of PCDDF were 5–
328 22 times higher in the fine fraction (2,990–45,770 ng TEQ=kg)
329 than in the coarse fraction (520–1,340 ng TEQ=kg). A comparison
330 of the concentrations of dioxin and furans substituted at the same
331 position showed that the concentrations of dioxin compounds
332 seemed to be higher than those of furan compounds in the different
333 soil fractions and for all of the soils studied.
334 Efficiencies of Attrition Treatment on the Coarse
335 Fraction (>0.125 mm)
336 Three attrition steps 20 min each, carried out at room temperature
337 with a pulp density fixed at 40% (w/w), were applied to the coarse
338 fraction (4–12, 1–4, and 0.125–1 mm) of the different soils studied.
339
Performance of Attrition on Inorganic and Organic
340
Contaminant Removal
341
Table3show the concentrations of As, Cr, Cu, PCP, and PCDDF
342
measured in the recombined soil fraction (>0.125 mm) before
343
and after treatment by attrition and the associated removal yields.
344
After the treatment by attrition, the residual concentrations of
in-345
organic contaminants in the coarse fraction (>0.125 mm
recom-346
bined soil fraction) ranged from 19 to37 mg As=kg, from 22 to
347
195 mg Cr=kg, and from 41 to 67 mg Cu=kg. The entire attrition
348
process allowed the removal of 24–42% of As, 0–13% of Cr, and
349
23–46% of Cu. According to a study by Williford et al. (1999), a
350
pretreatment by attrition allowed similar removal yields (26.8% for
351
Cr) to those observed in the present study. The low efficiencies of
352
As, Cr, and Cu removal observed during the attrition process can be
Table 2. Concentrations of Each Dioxin and Furan Measured in the Different Soil Fractions from Four Different Soils Studied
T2:1 Dioxin or furan Toxicity factora
Associated TEQ (ng=kg) Associated TEQ (ng=kg)
T2:2 D1(B) G2B) S1(A) S3(C) D1(B) G2(B) S1(A) S3(C) T2:3 0.125–12 mm 0.125–25 mm 0.125–12 mm 0.125–12 mm <0.125 mm <0.125 mm <0.125 mm <0.125 mm T2:4 Furans T2:5 2378-TCDF 0.1 0.18 0.40 0.24 1.43 4.59 2.50 3.38 9.98 T2:6 12378-PeCDF 0.05 0.44 0.87 0.64 3.66 8.80 5.30 5.70 19.4 T2:7 23478-PeCDF 0.5 4.15 9.25 6.50 33.2 92.5 46.8 65.0 266 T2:8 123478-HxCDF 0.1 9.88 28.2 23.8 204 203 226 239 1,480 T2:9 123678-HxCDF 0.1 9.10 22.8 14.1 118 221 140 154 775 T2:10 234678-HxCDF 0.1 16.7 53.3 29.1 305 361 376 298 321 T2:11 123789-HxCDF 0.1 0.41 2.33 1.03 10.7 6.78 9.75 8.55 2,020 T2:12 1234678-HpCDF 0.01 37.3 130 87.2 644 846 896 897 4,080 T2:13 1234789-HpCDF 0.01 2.58 10.7 6.03 61.0 57.1 78.4 62.6 393 T2:14 OCDF 0.001 21.4 83.6 65.6 389 405 674 576 2,020 T2:15 Dioxins T2:16 2378-TCDD 1 7.00 18.6 5.10 27.4 104 135 67.5 176 T2:17 12378-PeCDD 0.5 49.0 135 63.0 332 1,060 785 715 2,300 T2:18 123478-HxCDD 0.1 22.8 78.6 42.1 268 532 554 377 1,590 T2:19 123678-HxCDD 0.1 40.4 158 78.9 834 910 996 846 6,360 T2:20 123789-HxCDD 0.1 44.5 147 75.3 584 1,010 958 804 3,860 T2:21 1234678-HpCDD 0.01 131 774 303 3,010 2,680 4,520 2,720 12,800 T2:22 OCDD 0.001 123 837 276 2,360 2,840 5,830 2,630 7,300 T2:23 Total 520 2,489 1,078 9,185 11,342 16,233 10,469 45,770
aFrom OTAN and CDSM (1988).
Table 3. Concentrations of Contaminants Measured in the Recombined 0.125–12 mm or 0.125–25 mm before and after Treatment by Attrition
T3:1 Soils Contaminants T3:2 As (mg=kg) Cr (mg=kg) Cu (mg=kg) PCP (mg=kg) PCDDF (ng=kg) T3:3 Before attrition T3:4 D1 34.0 153 92.0 0.09 520 T3:5 G2 64.0 67.0 123 0.36 2,489 T3:6 S1 38.0 186 67.0 2.15 1,078 T3:7 S3 28.0 25.0 53.0 11.8 8,885 T3:8 After attrition T3:9 D1 26.0 133 63.0 0.05 332 T3:10 G2 37.0 87.0 67.0 1.18 2,055 T3:11 S1 22.0 195 46.0 0.33 387 T3:12 S3 19.0 22.0 41.0 7.92 3,213 T3:13 Removal yield (%) T3:14 D1 24 13 32 44 36 T3:15 G2 42 0 46 0 17 T3:16 S1 42 0 31 85 64 T3:17 S3 32 12 23 33 64
P
R
O
O
F
O
N
L
Y
353 attributed to the fact that the solubilization of these metals isun-354 favorable at pH¼ 7, and only a small proportion of the inorganic
355 contaminants is fixed to the fine particles agglomerated to the
356 coarse particles and dislodged by attrition. Usually, attrition is used
357 as a pretreatment to enhance the performance of inorganic
contam-358 inant removal by gravimetric separation technologies and not as a
359 treatment itself. However, the attrition process developed seemed
360 to be efficient enough to remove As, Cr, and Cu from the coarse
361 fractions and allow the potential reutilization of the treated soils,
362 depending on the current national regulations.
363 Concerning the organic contaminants, the residual PCP and
364 PCDDF concentrations measured in the coarse fraction ranged
365 from 0.05 to7.92 mg=kg and from 332 to 3,213 ng TEQ=kg,
re-366 spectively. According to these results, the attrition process seemed
367 to be more efficient for the removal of PCP and PCDDF from Soils
368 S1 and S3, with removal yields ranging from 33 to 85% for PCP
369 and 64% for PCDDF, than from Soils G2 and D1, with removal
370 yields varying between 0 and 44% for PCP and between 17 and
371 36% for PCDDF. These results showed that the effect of attrition
372 could be influenced by the nature of the soil and the type of
con-373 taminant. In the case of Soils G2 and D1, the performance of
374 attrition to remove organic contaminants from the coarse particles
375 might be improved by the use of an amphoteric surfactant, thus
376 enhancing the solubilization of these hydrophobic organic
377 contaminants.
378 Attrition Sludge Production
379 The attrition steps produced sludge that represented between 0.7
380 and 6.1% for the fraction 0.125–1 mm, between 8.1 and 31%
381 for the fraction 1–4 mm, and between 8.0 and 20% for the fraction
382 4–12 mm of the total mass of the four different soils studied. Except
383 for Soil S1, the amount of sludge produced during attrition
in-384 creased as the size of the particles treated by attrition increased.
385 This effect can be a result of the more important disintegration
386 of agglomerated particles from the coarser soil fraction during
387 attrition.
388 Table4presents the amount of sludge produced during attrition
389 treatment of the coarse fraction (>0.125 mm) and the inorganic and
390 organic contaminant contents measured in the sludge. Depending
391 on the soils treated by attrition, the total amount of sludge produced
392 varied between 11.5 and 32.9% of all soil treated (coarse and fine
393 fraction). The treatment by attrition of the coarse fraction, which
394 represented between 80.8 and 96.3% of the soil, allowed the
con-395 centration of both inorganic and organic contaminants in small
396 amounts of sludge, except for Cr. The attrition sludge can be
dis-397 posed of in landfill sites or must be treated or disposed of in secured
398 landfill sites, depending on the residual concentrations of
contam-399 inants and the regulations.
400 These results highlighted that attrition is an inexpensive and
401 promising technique to simultaneously remove inorganic and
or-402 ganic contaminants from the coarse particles of soil and concentrate
403
them into small amounts of sludge, even if its performance seemed
404
to vary, depending on the nature of both soil and contaminant and
405
the initial levels of organic and inorganic contaminants.
406
Efficiencies of Chemical Leaching Treatment on the
407
Fine Fraction
408
Three leaching steps 2 h each were applied to the fine soil fraction
409
(<0.125 mm) of four different soils at 80 7°C to evaluate the
410
removal efficiencies of both organic and inorganic contaminants.
411
The pulp density was fixed at 10% (w/w), and the leaching solution
412
was composed of NaOH (1 M) and an amphoteric
surfac-413
tant½ðBWÞ ¼ 3% ðw=wÞ.
414
Performance of the Leaching Process on Inorganic and
415
Organic Contaminant Removal
416
Table5shows the contents of As, Cr, Cu, PCP, and PCDDF
mea-417
sured in the fine soil fraction (<0.125 mm) before and after
treat-418
ment by alkaline leaching and the associated removal yields. These
419
results highlight the necessity to develop an efficient method of
420
decontamination to allow the simultaneous removal of both organic
421
(PCP and PCDDF) and inorganic (As and Cu) contaminants.
422
After three alkaline leaching steps, the residual concentrations
423
of inorganic contaminants in the fine fraction (<0.125 mm) ranged
424
from 30.0 to99 mg As=kg, from 141 to 286 mg Cr=kg, and from
425
129 to234 mg Cu=kg. These results show that the entire leaching
426
process was quite effective in solubilizing inorganic contaminants,
427
especially As and Cu, with removal yields ranging from 87 to 95%
428
for As and from 73 to 84% for Cu, whereas it seemed to be
rel-429
atively less effective in the removal of Cr (from 50 to 72% of
430
Cr removed) from the different soils studied. These removal yields
431
were slightly higher than those observed by Reynier et al. (2014)
432
after three 2-h leaching steps carried out at 80°C in the presence of
433
NaOH (0.75 M) and BW [3% (w/w)] with a PD fixed at 10% (w/w).
434
Indeed, these authorsobtained removal yields between 70 and 89% 13 435
for As, between 23 and 66% for Cr, between 59 and 71% for Cu,
436
and between 77 and 90% for PCP. The difference observed can be
437
attributed to the fact that the concentration of NaOH used in the
438
present study was fixed at 1 M, thus increasing the solubilization
439
of metals under anionic forms. According to Reynier et al. (2015),
440
As was mainly solubilized as AsO3−4 and HAsO2−4 (<1%) during
Table 4. Sludge Production and Contaminant Concentrations Measured in the Sludge Produced during the Treatment of the 0.125–12 mm or 0.125– 25 mm Soil Fractions by Attrition
T4:1 Soils D1 G2 S1 S3
T4:2 Dry sludge production (kg=t) 115 329 194 121
T4:3 As content (mg=kg) 69.0 110 84.0 73.0
T4:4 Cr content (mg=kg) 247 32.0 163 42.0
T4:5 Cu content (mg=kg) 229 219 125 119
T4:6 PCP content (mg=kg) 0.31 0.01 7.18 32.8
T4:7 PCDD/F content (ng TEQ=kg) 1,400 3,220 3,000 30,620 Note: Three Attrition Steps, PD¼ 40%, T ¼ 20°C, t ¼ 20 min.
Table 5. Concentrations of Contaminants Measured in the Soil Fraction <0.125 mm before and after Leaching Treatment
T5:1 Soils Contaminants T5:2 As (mg=kg) Cr (mg=kg) Cu (mg=kg) PCP (mg=kg) PCDDF (ng=kg) T5:3 Before leaching T5:4 D1 286 374 559 4.43 11,342 T5:5 G2 776 575 965 5.9 16,233 T5:6 S1 554 401 681 54.9 10,469 T5:7 S3 664 509 830 191 45,800 T5:8 After leaching T5:9 D1 30.0 168 149 2.12 7,439 T5:10 G2 99.0 286 234 0.60 11,917 T5:11 S1 33.0 196 174 22.3 2,778 T5:12 S3 31.0 141 129 0.28 15,391 T5:13 Removal yield (%) T5:14 D1 90 55 73 52 34 T5:15 G2 87 50 76 90 27 T5:16 S1 94 51 74 59 73 T5:17 S3 95 72 84 100 66
Note: Three Leaching Steps, PD¼ 10%, T ¼ 80°C, t ¼ 2 h, ðNaOHÞ ¼ 1.0 M.
P
R
O
O
F
O
N
L
Y
441 alkaline leaching ½ðNaOHÞ ¼ 0.75 M, whereas Cr and Cu were442 mainly solubilized as CrðOHÞ−4 and CrO−2 for Cr and as
443 CuðOHÞ2−4 and CuðOHÞ−3 (<1%) for Cu.
444 Concerning the organic contaminants, the residual PCP and
445 PCDDF concentrations measured in the fine fraction ranged from
446 0.3 to22 mg=kg and from 2,780 to 15,391 ng TEQ=kg (Table5),
447 respectively. According to these results, the alkaline leaching
pro-448 cess seemed to be highly efficient for the removal of PCP and
449 PCDDF from the different soils studied, except for the removal
450 of PCDDF from Soils G2 and D1 and the removal of PCP from
451 Soil S1. The alkaline leaching process developed in the present
452 study allowed the removal of 52–100% of PCP and 27–73% of
453 PCDDF. These removal yields were slightly lower than those
454 observed by Reynier et al. (2014) after a similar leaching process
455 carried out on 1–6 mm contaminated soil fraction (>92% for PCP
456 and >81% for PCDDF). The differences observed could be
ex-457 plained by the fact that it is more difficult in the present study
458 to efficiently remove organic contaminants from the fine fraction
459 owing to their very high initial contents of PCP and PCDDF.
460 According to results of the present study, the performance of the
461 leaching process in the removal of organic contaminants might be
462 influenced by the nature of the soil and/or the type of contaminants.
463 Indeed, the performance of the leaching process seemed to be more
464 variable for the removal of PCP and PCDDF from soil than for
465 As, Cr, and Cu. However, these results highlighted that the use
466 of NaOH in combination with an amphoteric surfactant BW is
ef-467 ficient to simultaneously reduce the concentration of As, Cr, Cu,
468 PCP, and PCDDF from soils with different levels of contamination.
469 Leachates Treatment by Precipitation and Sludge
470 Production
471 The primary disadvantage of using chemical processes to remove
472 contaminants from soils is the production of large amounts of
al-473 kaline leachates that should be treated to concentrate the
contam-474 inants into small amounts of sludge. Table6presents the amount of
475 sludge produced during the treatment of alkaline leachates by
pre-476 cipitation–coagulation and the inorganic and organic contaminant
477 contents measured in the sludge.
478 Depending on the fine soil fraction treated by leaching, the total
479 amount of sludge produced during the treatment of leachates by
480 precipitation–coagulation varied between 1.1 and 3.7% (w/w) of
481 all soil treated. The treatment by precipitation–coagulation of
alka-482 line leachates concentrated the inorganic and organic contaminants,
483 especially PCDDF, in small amounts of sludge, thus reducing the
484 costs related to waste disposal. Indeed, the treatment of leachates
485 by precipitation–coagulation at pH ¼ 7 in the presence of ferric
486 ions allowed the precipitation of metals as CrðOHÞ3, CuðOHÞ2,
48714 Cu3ðAsO4Þ:2H2O or FeAs2H2Oor the adsorption of metals onto
488 ferric hydroxides or oxy-hydroxides (Reynier et al. 2015).
More-489 over, the precipitation of ferric hydroxides or oxy-hydroxides
490 enhances the removal of hydrophobic organic contaminants such
491
as PCP and PCDDF, allowing their adsorption by electrostatic
in-492
teractions (van der Waals interactions) on the flocs produced.
493
The contaminant contents measured in the sludge produced
494
during precipitation–coagulation varied between 975 and
495
2,550 mg As=kg (dry basis), between 930 and 1,500 mg Cr=kg,
496
between 1,690 and 2,820 mg Cu=kg, between 11.1 and
497
699 mg PCP=kg, and between 23,400 and 128,000 ng TEQ=kg,
de-498
pending on the initial level of contamination present in the fine soil
499
fraction (<0.125 mm). Owing to the large amounts of both organic
500
and inorganic contaminants measured in sludge, these residues
501
should be properly and safely managed according to the regulations
502
established in the country.
503
Economic Analysis
504
Table7presents the cost related to the treatment of different soils
505
contaminated by As, Cr, Cu, PCP, and PCDDF by attrition
506
(>0.125 mm soil fraction) and alkaline leaching (<0.125 mm soil
507
fraction) (Scenario 1), whereas Table8presents the cost related to
508
the treatment of the coarse fraction by attrition and the landfilling of
509
the fine fraction (Scenario 2). The total cost, expressed in US$=t,
510
include the direct, indirect, and capital costs estimated for the
511
decontamination of 15,000 t of contaminated soils per year.
512
The global cost related to the decontamination of different soils
513
contaminated by As, Cr, Cu, PCP, and PCDDF ranged from
514
US$353 to US$521=t for Scenario 1 and from US$235 to
515
US$443=t for Scenario 2. As expected, the main parameters
516
impacting the decontamination cost are the performance of both
517
the attrition and alkaline leaching processes and the ultimate
518
amounts of heavily contaminated soil and hazardous wastes
(met-519
allic sludge) to be appropriately disposed of. Indeed, if the attrition
520
or alkaline leaching processes did not sufficiently reduce both
521
organic and inorganic contaminants, the soil fraction should be
Table 6. Concentration of Inorganic and Organic Contaminants in the Sludge Obtained after Treatment of the Leachate by Precipitation– Coagulation with Ferric Sulfate
T6:1 Soils D1 G2 S1 S3
T6:2 Dry sludge production (kg=t) 33 30 11 37
T6:3 As content (mg=kg) 975 2,550 1,900 2,350
T6:4 Cr content (mg=kg) 964 1,280 930 1,500
T6:5 Cu content (mg=kg) 1,690 2,820 2,020 2,710
T6:6 PCP content (mg=kg) 11.1 20.0 140 699
T6:7 PCDD/F content (ng TEQ=kg) 23,400 24,200 30,800 128,000
Table 7. Direct and Indirect Costs Related to the Treatment by Attrition (>0.125 mm) and Alkaline Leaching (<0.125 mm) of Different Soils Contaminated by As, Cr, Cu, PCP, and PCDDF
T7:1
Soil sample D1 G2 S1 S3
T7:2
Direct operating costs (US$=t)
T7:3 Chemicals T7:4 Surfactant (BW) 10.11 9.27 3.37 11.29 T7:5 Sodium hydroxide 22.47 20.60 7.49 25.09 T7:6 Sulfuric acid 11.51 10.55 3.84 12.85 T7:7 Ferric chloride 0.04 0.04 0.01 0.05 T7:8 Labor T7:9
Operating and maintenance staff 23.03 13.03 23.03 23.03
T7:10 Utilities T7:11 Electricity 3.03 3.40 3.16 3.51 T7:12 Process water 0.05 0.04 0.02 0.05 T7:13 Fuel 13.51 12.38 4.50 15.09 T7:14
Transport and disposal of soil (C-D) (120 US$=t)
17.33 106 5.77 127
T7:15 Transport and disposal of
hazardous wastes and highly contaminated soils (US$500=t)
82.26 148 154 90.19
T7:16
Total direct operating cost 213.27 355.50 230.00 331.25
T7:17
Indirect and general costs (US$=t)
T7:18
Administrative staff 3.47 3.45 3.45 3.45
T7:19
Insurance and taxes 18.19 18.30 13.20 19.41
T7:20 Capital cost T7:21 Depreciation 67.71 70.14 50.62 74.41 T7:22 Debt service 43.84 44.11 31.83 46.80 T7:23
Total indirect and capital costs 158.04 165.27 122.49 172.29
T7:24
P
R
O
O
F
O
N
L
Y
522 disposed of in an appropriate secured landfill site, increasing the523 decontamination cost. The amounts of sludge produced during the
524 attrition and precipitation of leachates also significantly impacted
525 the cost of decontamination, ranging from US$82 to US$154=t for
526 Scenario 1 and from US$151 to US$282=t for Scenario 2. These
527 results highlighted that the treatment of the fine fraction by leaching
528 allowed a significant reduction in the volume of highly
contami-529 nated soil to be appropriately disposed of. However, the chemical
530 cost related to the treatment of the fine fraction by alkaline
leach-531 ates and the treatment of effluents by precipitation were estimated
532 to be US$15–50=t, depending on the nature of the soil and the
ini-533 tial level of contamination. These costs revealed the necessity of
534 treating only a small proportion of the contaminated soil and to
535 favor physical decontamination methods such as attrition for the
536 coarse particles to reduce the direct and investment costs.
537 The indirect and capital costs accounted for between 32 and
538 43% of the total decontamination cost for Scenario 1 and between
539 15 and 24% for Scenario 2. The differences observed were
pri-540 marily a result of the highest investment cost obtained when the
541 fine fraction of the soils was treated by alkaline leaching
(approx-54215 imately US$10 million) compared to the investment costs of
Sce-543 nario 2 (approximately US$4 million).
544 According to these results, Scenario 2 seemed to be less
expen-545 sive than Scenario 1 for all soils studied (US$353–521=t for
546 Scenario 1 versus US$235–443=t for Scenario 2). A
technico-547 economic evaluation has been made with different treatment plant
548 capacities varying from 48 t per day (15,000 t per year) and 100 t per
549 day (31,500 t per year). The results presented in Table9show that the
550 increased treatment plant capacities from 48 to100 t=day
signifi-551 cantly reduced the decontamination costs from US$353–521=t
552 to US$299–455=t for Scenario 1 and from US$233–443=t to
553 US$214–421=t for Scenario 2. An increase in the treatment
554 capacities of the decontamination plant from 15,000 t=year to
555
31,500 t=year allowed a reduction in the total costs ranging from
556
US$21 to US$69=t, depending on the soil and the decontamination
557
process. The estimated global cost was much lower than the actual
558
cost (US$600=t) related to the secure landfilling of these
contami-559
nated soils (Reynier 2012). In other words, the entire
decontami-560
nation process, with or without the treatment of the fine fraction by
561
alkaline leaching, is highly competitive with current disposal
op-562
tions (thermal desorption and landfilling or incineration in a cement
563
kiln) (Reynier et al. 2013).
564 Conclusion
565
The inappropriate management and/or storage of PCP- and
CCA-566
treated wood over the last few decades has led to the contamination
567
of several sites across the world. The primary contaminants found
568
in these sites are As, Cr, Cu, PCP, and PCDDF. The present work
569
evaluates the performance and the robustness of a decontamination
570
process able to simultaneously remove inorganic and organic
con-571
taminants using an attrition process for the coarse particles and an
572
alkaline leaching process for the fine particles. Satisfactory removal
573
yields were observed for both organic and inorganic contaminants
574
from the four different soils studied (24–42% of As, 0–13% of Cr,
575
23–46% of Cu, 0–85% of PCP, and 17–64% of PCDDF). The
576
present results also highlighted that the combination of NaOH
577
and BW is highly efficient to simultaneously remove organic
578
and inorganic contaminants from the fine fraction of contaminated
579
soil. This process extracted 87–95% of As, 50–72% of Cr, 73–84%
580
of Cu, 52–100% of PCP, and 27–73 of PCDDF from different
581
contaminated soils after three leaching steps [ðNaOHÞ ¼ 1 M,
582
ðBWÞ ¼ 3% (w/w), t ¼ 2 h, PD ¼ 10% (w/w)]. These results
583
highlighted that the entire leaching process is effective for
simul-584
taneous removal of inorganic and organic contaminants. However,
585
the nature of the soil and the type and initial level of contaminants
586
present in the soil seemed to influence the performance of both the
587
attrition and alkaline leaching processes. The cost, including direct
588
and indirect costs, was estimated between US$235 and US$521 per
589
ton of treated soil, depending on the nature of the soil, the initial
590
level of contamination, and the scenario applied to the fine soil
frac-591
tion (alkaline leaching or secured disposal).
592 References
593 Anderson, R., Rasor, E., and Van Ryn, F. (1999).“Particle size separation
594 via soil washing to obtain volume reduction.” J. Hazard. Mater.,
595
66(1–2), 89–98.
596 APHA (American Public Health Association). (1999). Standards methods
597 for examination of water and wastewaters, 20th Ed., Washington, DC. Table 8. Direct and Indirect Costs Related to the Treatment by Attrition
(>0.125 mm) and Disposal of the Fine Fractions (<0.125 mm) of Different Soils Contaminated by As, Cr, Cu, PCP, and PCDDF
T8:1 Soil sample D1 G2 S1 S3
T8:2 Direct operating costs (US$=t)
T8:3 Chemicals T8:4 Surfactant (BW) 0.00 0.00 0.00 0.00 T8:5 Sodium hydroxide 0.00 0.00 0.00 0.00 T8:6 Sulfuric acid 0.00 0.00 0.00 0.00 T8:7 Ferric chloride 0.00 0.00 0.00 0.00 T8:8 Labor
T8:9 Operating and maintenance staff 10.2 10.2 10.2 10.2
T8:10 Utilities
T8:11 Electricity 2.93 3.18 2.93 3.34
T8:12 Process water 0.00 0.00 0.00 0.00
T8:13 Fuel 0.00 0.00 0.00 0.00
T8:14 Transport and disposal of soil (C-D)
0.00 69.93 0.00 106 T8:15 Transport and disposal of
hazardous wastes and highly contaminated soils (500 US$=t)
151 282 156 164
T8:16 Total direct operating costs 179.73 374.17 185.37 292.11
T8:17 Indirect and general costs
T8:18 Administrative staff 1.53 1.53 1.53 1.53
T8:19 Insurance and taxes 5.51 6.16 5.53 6.03
T8:20 Capital costs
T8:21 Depreciation 21.13 23.62 21.19 23.11
T8:22 Debt service 13.29 14.86 13.33 14.54
T8:23 Total indirect and capital costs 55.31 68.80 55.68 64.13
T8:24 Net costs 235.04 442.97 241.05 356.24
Table 9. Determination of the Direct and Indirect Costs Related to the Decontamination of Different Soils Contaminated by As, Cr, Cu, PCP, and PCDDF Depending on the Treatment Plant Capacity
T9:1
Scenario Soil
Total cost (US$=t)
T9:2 (15,000 t=year) (31,500 t=year) T9:3 1 D1 371.31 305.25 T9:4 G2 520.77 454.84 T9:5 S1 352.49 299.62 T9:6 S3 503.55 434.61 T9:7 2 D1 235.04 214.39 T9:8 G2 442.97 421.16 T9:9 S1 241.05 220.37 T9:10 S3 356.24 334.56
P
R
O
O
F
O
N
L
Y
598 Bergeron, M., Blackburn, D., and Gosselin, A. (1999).“Protocoled’évalu-599 ation de la traitabilité des sédiments, des sols et des boues à l’aide des
600 technologies minéralurgiques.” Ministère des travaux publics et
601 servives gouvernementaux du Canada, Québec, Canada, (in French).
602 Bisone, S. (2012).“Décontamination de sols contaminés par du cuivre du
603 zinc et des HAP provenant de déchets métallurgiques.” Ph.D. thesis,
604 INRS-ETE, Université du Québec, Québec, QC, Canada, 209 605 (in French).
606 Blais, J. F., Djedidi, Z., Cheikh, R. B., Tyagi, R. D., and Mercier, G. (2008).
607 “Metals precipitation from effluents: Review.” Pract. Period. Hazard. 608 Toxic Radioactive Waste Manage.,10.1061/(ASCE)1090-025X(2008)
609 12:3(135), 135–149.
610 CEAEQ (Centre d’Expertise en Analyse Environnementale du Québec).
611 (2011).“Détermination des dibenzo-para-dioxines polychlorés et
di-612 benzofuranes polychlorés: Dosage par chromatographie en phase
gaz-613 euse couplée à un spectromètre de masse.” MA. 400-D.F. 1.1, Ministère
614 du Développement Durable, de l’Environnement et des Parcs du 61516 Québec, Québec, QC, Canada, (in French).
616 CEAEQ (Centre d’Expertise en Analyse Environnementale du Québec).
617 (2013).“Détermination des composés phénoliques: Dosage par
chro-618 matographie en phase gazeuse couplée à un spectromètre de masse 619 après dérivation avec l’anhydride acétique.” MA. 400-Phé 1.0,
Minis-620 tère du Développement Durable, de l’Environnement et des Parcs du
621 Québec, Québec, QC, Canada, (in French).
622 Cooper, P. A., and Ung, Y. T. (1997).“Effect of water repellents on leaching
623 of CCA from treated fence and deck units-An update.” IRG/WP
62417 97-50086, International Research Group on Wood Protection. 625 Coudert, L., Blais, J. F., Mercier, G., Cooper, P., Janin, A., and Gastonguay,
626 L. (2014).“Demonstration of the efficiency and robustness of an acid
627 leaching process to remove metals from various CCA-treated wood
628 samples wastes of various ages.”J. Environ. Manage., 132, 197–206.
629 Dermont, G., Bergeron, M., Mercier, G., and Richer-Lafleche, M. (2008).
630 “Soil washing for metal removal: A review of physical/chemical 631 technologies and field applications.”J. Hazard. Mater., 152(1), 1–31.
632 Doyle, C. (2008).“La phytoremédiation: Une solution à la contamination
633 des sites de traitement du bois?” Sherbrooke Univ., Sherbrooke, QC,
63418 Canada, (in French).
635 Dufresne, M. (2013).“Les technologies de traitement des sols contaminés:
636 Lesquelles sont durables?” M.S. thesis, Sherbrooke Univ., Quebec, QC,
637 Canada, (in French).
638 Hasan, A. R., Hu, L., Solo-Gabriele, H. M., Fieber, L., Cai, Y., and 639 Townsend, T. G. (2010).“Fieldscale leaching of arsenics, chromium
640 and copper from weathered treated wood.”Environ. Pollut., 158(5),
641 1479–1486.
642 Janin, A. (2009).“Développement d’un procédé chimique de
décontami-643 nation de bois usagé traité à l’arséniate de cuivre chromaté.” Ph.D.
644 thesis, INRS-ETE, Université du Québec, Québec, QC, Canada, (in 645 French).
646 Kasai, E., Harjanto, S., Terui, T., Nakamura, T., and Waseda, Y. (2004).
647 “Thermal remediation of PCDDFs contaminated soil by zone combus-64819 tion process.”Chemosphere, 41(6), 857–864.
649 Kulkarni, P. S., Crespo, J. G., and Afonso, C. A. M. (2008).“Dioxins sour-650 ces and current remediation technologies—A review.” Environ. Int.,
651 34(1), 139–153.
652 Lafond, S., Blais, J. F., Martel, R., and Mercier, G. (2012).“Chemical 653 leaching of antimony and other metals from small arms shooting range 654 soil.”Water Air Soil Pollut., 224(1), 1371–1386.
655 Lecomte, P. (1998). Les sites pollués: Traitement des sols et des eaux 656 souterraines, Lavoisier, Paris, 204 (in French).
657 Mao, X., Jianga, R., Xiaoa, W., and Yu, J. (2015).“Use of surfactants for
658 the remediation of contaminated soils: A review.”J. Hazard. Mater.,
659
285, 419–435.
660
Mouton, J., Mercier, G., and Blais, J. F. (2009).“Amphoteric surfactants for
661
PAH and lead polluted-soil treatment using flotation.”Water Air Soil
662
Pollut., 197(1), 381–393.
663
Napola, A., Pizzigallo, M. D. R., Di Leo, P., Spagnuolo, M., and Ruggiero,
664
P. (2006).“Mechanochemical approach to remove phenanthrene from a 665 contaminated soil.”Chemosphere, 65(9), 1583–1590. 20
666
OTAN and CDSM (Organisation du Traité de l’Atlantique Nord and
667
Comité sur les Défis de la Société Moderne). (1988). “Pilot study
668
on international information exchange on dioxins and related com-669 pounds. International Toxicity Equivalency Factor (I-TEF) method of
670
risk assessment for complex mixtures of dioxins and related
com-671
pounds.” Rep. No. 176,. 21
672
Pociecha, M., and Lestan, D. (2012).“Washing of metal contaminated soil
673
with EDTA and process water recycling.”J. Hazard. Mater., 235–236,
674
384–387. 22
675 Reynier, N. (2012).“Décontamination des sols pollués par des métaux, du
676
pentachlorophénol et des dioxines et furanes.” Ph.D. thesis, INRS-ETE,
677
Université du Québec, Québec, QC, Canada, (in French).
678
Reynier, N., Blais, J. F., Mercier, G., and Besner, S. (2013).“Treatment of 679 arsenic-, chromium-, copper- and pentachlorophenol-polluted soil using
680
flotation.”Water Air Soil Pollut., 224(4), 1514–1526. 23
681
Reynier, N., Blais, J. F., Mercier, G., and Besner, S. (2014).
“Decontami-682
nation of metals, pentachlorophenol, and polychlorined
dibenzo-p-683
dioxins and dibenzofurans polluted soil in alkaline conditions using
684
an amphoteric biosurfactant.”Environ. Technol., 35(2), 177–186. 24 685 Reynier, N., Coudert, L., Blais, J. F., Mercier, G., and Besner, S. (2015).
686
“Treatment of contaminated soil leachate by precipitation, adsorption
687
and ion exchange.”J. Environ. Chem. Eng., 3(2), 977–985.
688
Rivero-Huguet, M., and Marshall, W. D. (2011).“Scaling up a treatment to 689 simultaneously remove persistent organic pollutants and heavy metals
690 from contaminated soils.”Chemosphere, 83(5), 668–673.
691 Stefanovic, S., and Cooper, P. (2005).“Effects of soil physical and chemical
692 characteristics on adsorption of leached CCA and ACQ preservative
693 components.” IRG/WP 03-50, International Research Group on Wood
694 Protection, Brisbane, Australia.
695 Stilwell, D. E., and Graetz, T. J. (2001).“Copper, chromium, and arsenic
696 levels in soil near highway traffic sound barriers built using CCA
697 pressure-treated wood.” Bull. Environ. Contamin. Toxicol., 67(2),
698
303–308. 2526
699 Subramanian, B., Namboodiri, V., Khodadoust, A. P., and Dionysiou, D. D.
700
(2010).“Extraction of pentachlorophenol from soils using
environmen-701
tally benign lactic acid solutions.”J. Hazard. Mater., 174(1–3), 263–
702
269.
703
Taillard, V. (2010). “Démonstration à l’échelle pilote d’un procédé d’
704
extraction simultanée des HAP et du plomb.” M.S. thesis, INRS-705 ETE, Université du Québec, Québec, QC, Canada,(in French).
706
Torres, L. G., Lopez, R. B., and Beltran, M. (2012).“Removal of As, Cd,
707
Cu, Ni, Pb, and Zn from a highly contaminated industrial soil using
708
surfactant enhanced soil washing.” Phys. Chem. Earth Parts A/B/C,
709
37–39, 30–36. 27
710
Voglar, D., and Lestan, D. (2013).“Pilot-scale washing of Pb, Zn and Cd
711
contaminated soil using EDTA and process water recycling.”
Chemo-712
sphere, 91(1), 76–82.
713
Williford, C. W., Li, Z., Wang, Z. M., and Bricka, R. M. (1999).“Vertical
714
column hydroclassification of metal-contaminated soils.”J. Hazard.
715
P
R
O
O
F
O
N
L
Y
Queries
1. Please provide the ASCE Membership Grades for the authors who are members.
2. [ASCE Open Access: Authors may choose to publish their papers through ASCE Open Access, making the paper freely available to all readers via the ASCE Library website. ASCE Open Access papers will be published under the Creative Commons-Attribution Only (CC-BY) License. The fee for this service is $1750, and must be paid prior to publication. If you indicate Yes, you will receive a follow-up message with payment instructions. If you indicate No, your paper will be published in the typical subscribed-access section of the Journal.]
3. Please check the hierarchy of section heading levels.
4. The citation Rivero-Huguet et al. (2011) has been changed Rivero-Huguet and Marshall (2011 as per the list. Please check and confirm.
5. The citation Pociecha et al. (2012) has been changed as Pociecha and Lestan (2012) as per the list. Please check and confirm. 6. The citation Voglar et al. (2013) has been changed as Voglar and Lestan (2013) as per the list. Please check and confirm 7. By the phrase, " to the authors," which reference are you citing? It should be cited specifically.
8. Please provide the manufacturer’s information (city/state location) for the Sweco and the Fristh ball mill in this paragraph. 9. Please provide manufacturer information for the Imhoff cones.
10. ASCE prefers to avoid using first-person pronouns (we, our) and these have been changed throughout.
11. Please provide the city and state location of the manufacturer of the Accumet Model 915 and the Cole-Parmer electrode. 12. Please check the footnote for Table 2, which was relocated to the bottom of the table because it seems to only apply to the second
column. If the credit for OTAN and CDSM (1988) applies to the entire table, then the citation should be placed in the table title. Please advise.
13. By "these authors," are you referring to yourselves or to Reynier et al. (2014)? Please specify. 14. Should the dots in " Cu_3(AsO_4).2H_2O or FeAsO_4.2H_2O " rather be center dots? 15. Please check and confirm that US$10 million and US$4 million was your intended meaning. 16. Please check and confirm or correct the spellout of the acronym, CEAEQ.
17. For Cooper and Ung 1997, please provide the location of the International Research Group on Wood Protection.
18. Please check we have treated this reference as thesis. Hence please specify whether it is master or doctoral thesis for Doyle (2008).
19. Please check and confirm/correct the publication dates for Kasai et al. 2004 and Lafond et al. 2012. 20. Issue number ’9’ has been inserted in this reference. Please check and confirm the edit made here.
21. Please provide the publisher’s name and location for OTAN and CDSM. Also, verify that the capitalization in the spellout of the acronyms is correct.
22. Please provide issue number for Pociecha and Lestan (2012).
23. Issue number ’4’ has been inserted in this reference. Please check and confirm the edit made here. 24. Please check and confirm/correct the publication date for Reynier et al. 2014.
